• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.217-220
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• 2006

The lift and drag forces produced by a wing of a given cross-sectional profile are dependent on the wing planform and the angle of attack. Aspect ratio is the ratio of the wing span to the average chord. For conventional fixed wing aircrafts, high aspect ratio wings produce a higher lift to drag ratio than low ones for flight at subsonic speeds. Therefore, high aspect ratio wings are used on aircraft intended for long endurance. However, birds and insects flap their wings to fly in the air and they can change their wing motions. Their wing motions are made up of translation and rotation. Therefore, we tested flapping motions with parameters which affect rotational motion such as the angle of attack and the wing beat frequency. The half elliptic shaped wings were designed with the variation of aspect ratio from 4 to 11. The flapping device was operated in the water to reduce the wing beat frequency according to Reynolds similarity. In this study, the aerodynamic forces, the time-averaged force coefficients and the lift to drag ratio were measured at Reynolds number 15,000 to explore the aerodynamic characteristics with the variation of aspect ratio. The maximum lift coefficient was turned up at AR=8. The mean drag coefficients were almost same values at angle of attack from $10^{\circ}$ to $40^{\circ}$ regardless of aspect ratio, and the mean drag coefficients above angle of attack $50^{\circ}$ were decreased according to the increase of aspect ratio. For flapping motion the maximum mean lift to drag ratio appeared at AR=8.

• Journal of Periodontal and Implant Science
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• 제25권2호
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• pp.407-417
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• 1995

In order to evaluate the effect of platelet-derived growth factor(PDGF-BB) and guided tissue regeneration(GTR) technique on the regeneration of destructed periodontal tissue,intentional through-and-through furcation defects(4mm in height) were made on both mandibular 2nd and 4th premolars of 8 adult male dogs(30-40lb). Experimental group 1 was composed of the premolars that were treated by only topical application of PDGF-BB with 0.05M acetic acid without any barrier membrane. Experimental group 2 was composed of the premolars that were treated by GTR with expanded polytetrafluoroethylene membrane(ePTFE : Gore-tex periodontal material, USA). Experimental group 3 was composed of the premolars that were treated by GTR with ePTFE after topical application of PDGFBE. Control group was composed of the premolars that were treated by coronally positioned flap operation only without use of PDGF-BB and ePTFE membrane. All ePTFE membranes were carefully removed 4 weeks after regenerative surgery, and all experimental animals were sacrificed 8 weeks after regenerative surgery. The light microscopic findings were as follows ; (1) In experimental group 1, rapid new bone formation along the-root surface with multiple ankylosis and root resorption by multinucleated giant cells, and dense connective tissue in the central portion of the furcation defects were observed. (2) In experimental group 2, it was observed that the furcation defects were filled with newly formed bone, Sharpey's fibers were embedded into new cementum on root dentin of furcation fornix area, but the central portion and the area under furcation fornix were still filled with dense connective tissue. (3) In experimental group 3, the furcation defects were regenerated with newly formed dense bone and regular periodontal ligament with Sharpey's fibers embedded into newly formed cementum and bone underneath fornix area. (4) In control group, unoccupied space, apical migration of epithelium, dense infiltration of inflammatory cells in subepithelial connective tissue in relation to heavy plaque accumulation, and root resorption by inflammatory reaction were shown, but any new cementum formation on resorbed dentin surface could not be observed. The present study demonstrated that the combined therapy of PDGF-BB and GTR could enhance the regeneration of destructed periodontal tissue.

• Archives of Plastic Surgery
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• 제32권3호
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• pp.397-402
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• 2005

For its lowerlid entropion correction, nonsurgical eyelid suture or surgical eyelid suture can be employed. Different types of surgical eyelid suture such as the Hotz method and the Callahan method, are generally performed, but were not sufficient for correcting of entropion. In our hospital we performed modified skin-tarsal fixation on 15 patients, 5 male and 10 female from January 20, 1999 to December 16, 2002. We corrected lower eyelid entropion with the excision of the skin and orbicularis oculi muscle and buried suture of tarsal plate and dermis which is a variant of the Callahan method. All the patients were satisfied with the operation results, and there was no case of recurrence of the lower eyelid pricking the cornea. During the 6 months period after the operation, the lower eyelids slightly turned inward but there was no further progression. The correction was performed excessively, therefore there was no case of recurrence after the operation and the results were satisfactory. There developed a dimple at the suture margin caused by skin contraction but it usually disappeared within 2 months after the operation. To avoid recurrence and to achieve satisfactory results, the orbicularis oculi muscle must be totally resected at the ciliary margin. We resected ciliary as well as pretarsal portion of orbicularis oculi muscle. Also, since most of the recurrences are originated from the medial side, the medial portion of skin flap must be tightly fixed to avoid recurrence and the upper part of the dermis should be fixed tightly to the lower border of the tarsal plate.

• Archives of Plastic Surgery
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• 제32권3호
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• pp.287-292
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• 2005

The definitive correction of secondary lip nasal deformities is a great challenge for plastic surgeons. To rectify the secondary lip nasal deformities, various procedures and its modifications have been reported in many centers. However, no universal agreement exist to correct the various components of secondary nasal deformities. The secondary nasal deformity of the unilateral cleft lip has its own characteristic abnormalities including the retroplaced dome of the ipsilateral nasal tip, hooding of the alar rim, a secondary alar-columellar web, short columella, depressed alar base and so forth. Among these components of secondary nasal deformity, maxillary hypoplasia, especially in the area of piriform aperture, and alveolar bone defect can make the alar base depressed, which in turn, leads to wide and flat nasal profile, obtuse nasolabial angle coupled with subnormal nasal tip projection in aspect of aesthetic consideration. Moreover, the maxillary hypoplasia contributes to reduced size of the nasal airway in combination with other component of external nasal deformity and therefore the nasal obstruction may be developed functionally. Therefore, the current authors have performed corrective rhinoplasty with the augmentation of alar base with various methods which include rearrangement of soft tissue, vertical scar tissue flap and use of allogenic or autologous materials in 42 patients between 1998 and 2003. The symmetric alar base could be achieved, which provides the more accurate evaluation and more appropriate management of the various component of any coexisting secondary nasal deformity. In conclusion, the augmentation of alar base, as a single procedure, is a basic and essential to correct the secondary lip nasal deformities.

• Archives of Plastic Surgery
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• 제40권4호
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• pp.387-391
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• 2013

Background The most common cutaneous malignant masses are basal cell carcinoma (BCC) and squamous cell carcinoma. The predominant site of a malignant mass is the face, which has many opportunities to be exposed to ultraviolet radiation. However the predilection sites of malignant masses have been equivocal due to the use of general regions, rather than anatomical landmarks, in surveys. A facial esthetic unit is an anatomical site classified as an area of similar facial contour characteristics that can be distinguished from other areas. The purpose of this study is to determine widely accepted anatomical landmarks using the esthetic unit. Methods We retrospectively analyzed 118 cases of malignant masses in our clinic from January 2005 to October 2012. We evaluated the patients' age, gender, and predilection site of the malignant mass by esthetic unit through pathology, medical records and patient photographs. We mapped the occurrence site of the malignant mass on schematic drawings of the esthetic units. Results Most of the malignant masses were BCC. The ratio of males to females was 1:1.41. The frequent predilection site of a malignant mass was on the nasal unit (33.1%), followed by the buccal unit (11.0%). Primary closure was the most common method of repairing a surgical defect (38.9%), followed by a local flap (35.5%). Conclusions This review described the relationship between clinical characteristics and esthetic units by proposing objective predilection sites for malignant masses, which can be used commonly as a framework in the study of malignant masses by unifying equivocal occurrence sites.

• Archives of Plastic Surgery
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• 제40권2호
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• pp.109-115
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• 2013

Background Breast reconstruction refers to the rebuilding of a woman's breast using autologous tissue or prosthetic material to form a natural-looking breast. It is increasingly offered to women undergoing mastectomy for breast cancer. However, there is no systematic analysis available for the expanding area of research on breast reconstruction. Methods A bibliometric method was used to obtain a view of the scientific production about breast reconstruction by data extracted from the Institute for Scientific Information (ISI). Specific parameters were retrieved from the ISI. Articles about breast reconstruction were analyzed to obtain a view of the topic's structure, history, and document relationships using HistCite software. Trends in the most influential publications and authors were analyzed. Results The number of articles was constantly increasing. Most highly cited articles described the methods of flap construction in the surgery. Other highly cited articles discussed the psychological or emotional aspects of breast reconstruction, skin sparing mastectomy, and breast reconstruction in the irradiated breast. Conclusions This was the first breast reconstruction scientometric analysis, representing the characteristics of papers and the trends of scientific production. A constant increase in the number of breast reconstruction papers and also the increasing number of citations shows that there is an increasing interest in this area of medical science. It seems that most of the research in this field is focused on the technical aspects of surgery.

• Archives of Plastic Surgery
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• 제40권4호
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• pp.374-379
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• 2013

Background To date, various types of acellular dermal matrix (ADM) have been developed for clinical use. AlloDerm is the most familiar type of ADM to most surgeons in breast reconstruction. It is prepared by freeze-drying. CG CryoDerm is the first form of ADM that requires no drying process. Therefore, theoretically, it has a higher degree of preservation of the dermal structures than AlloDerm. We conducted this study to compare the clinical course and postoperative outcomes of patients who underwent direct-to-implant breast reconstructions using AlloDerm and those who did using CG CryoDerm. Methods We performed a retrospective analysis of the medical records in a consecutive series of 50 patients who underwent direct-to-implant breast reconstruction using AlloDerm (n=31) or CryoDerm (n=19). We then compared the clinical course and postoperative outcomes of the two groups based on the overall incidence of complications and the duration of drainage. Results The mean follow-up period was 16 months. There were no significant differences in the overall incidence of complications (seroma, infection, skin flap necrosis, capsular contracture, and implant loss) between the two groups. Nor was there any significant difference in the duration of drainage. Conclusions CG CryoDerm has the merits of short preparation time and easy handling during surgery. Our results indicate that CG CryoDerm might be an alternative allograft material to AlloDerm in direct-to-implant breast reconstruction.

• Archives of Plastic Surgery
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• 제33권3호
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• pp.359-366
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• 2006

Acquired facial deformities following cancrum oris sequelae manifested variably according to the nature of tissue necrosis. In cases that tissue loss extends over a wide area of the face, or the tissue nature is different due to congenital facial cleft, it is difficult to reconstruct with a single operation. As cancrum oris has virtually disappeared from our country, clinical report of reconstruction is also rare. We report 5 cases of facial deformities following cancrum oris sequelae. Since 1988, five adult patients(4 female and 1 male) were treated by authors. These patients, with an age ranged from 47 to 58 years, all suffered from acquired facial cleft such as facial mutilation, asymmetry. The stages of operation were from 1 to maximum of 5 operations. All surgeries achieved satisfactory results after a long-term follow-up. But one surgery in the case of palatal mucosal flap for the coverage of reconstructed maxilla alveolar bone resulted tissue sloughness, followed by osteomyelitis. Those were debrided and discarded. In conclusion, all sites of deformities were positioned around one of the oral commissures. In their past medical history, they have been suffering from measles, typhoid fever and unknown febrile illness. We diagnosed the acquired facial deformity following cancrum oris sequelae. The reconstruction of acquired facial deformity following cancrum oris sequelae were difficult due to extensive multiple tissue defects. Therefore multiple staged operations were inevitable. The authors reconstructed 5 cases of simple and complex form of facial deformity with minimum staged operations. All patients were satisfied functionally and cosmetically.

• Archives of Plastic Surgery
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• 제33권3호
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• pp.383-387
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• 2006

Atypical fibroxanthoma is a pleomorphic spindle cell neoplasm characterized by a variable combination of cells with fibroblastic and histiocytic features. It occurs mostly on sun-exposed area of the head and neck of elderly person and is a clinically benign reactive lesion despite apparent malignant histologic features. However, because of its potential for metastasis, it is widely regarded as a low-grade sarcoma. We report a 30-year-old woman with atypical fibroxanthoma developed on the left occipital area. The lesion was $1.5{\times}2cm$ sized papule. There was no skin lesion such as ulcer or eschar. However, mass was involving occipital bone and composed of dense, pleomorphic spindle cells and several bizarre multinucleated giant cells. After wide excision of the scalp and occipital bone, the defect was covered with bone cement, bipedicled local flap and the donor site was covered with STSG. The wound healed completely without complication. It remained free of recurrence for a period of about 1 year follow up.

• Archives of Plastic Surgery
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• 제39권5호
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• pp.561-564
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• 2012

Nasal bone fractures are often accompanied by septal fractures or deformity. Posttraumatic nasal deformity is usually caused by septal fractures. Submucosal resection and septoplasty are commonly used surgical techniques for the correction of septal deviation. However, septal perforation or saddle nose deformity is a known complication of submucosal resection. Hence, we chose to perform septoplasty, which is a less invasive procedure, as the primary treatment for nasal bone fractures accompanied by septal fractures. During septoplasty, we used a bioabsorbable mesh as an internal splint. We used the endonasal approach and inserted the mesh bilaterally between the mucoperichondrial flap and the septal cartilage. The treatment outcomes were evaluated by computed tomography (CT) and the nasal obstruction symptom evaluation (NOSE) scale. The CT scans demonstrated a significant improvement in the septal deviation postoperatively. The symptomatic improvement rated by the NOSE scale was greater at 1 month and 6 months after surgery compared to the preoperative status. There were no cases of extrusion or infection of the implant. In cases of moderate or severe septal deviation without dislocation from the vomerine groove on the CT scan, our technique should be considered one of the treatments of choice.